Jellyfish warning for Cork beaches as warm temperatures set to continue

There have been reports of sightings of the venomous Portuguese Man o' War in recent days at several beaches in Co Cork

The Portuguese Man o' War jellyfish, which has reportedly been seen in some Cork beaches in recent days, can grow up to 12 inches long and five inches wide. File photo

Sunshine is forecast to continue into this weekend but with rising temperatures comes an increased risk of venomous jellyfish in Irish waters.

Although Cork City Council has received no official reports, the venomous and potentially deadly Portuguese Man o' War jellyfish was reportedly seen in beaches in Crosshaven and Garretstown, with a photo of the creature reportedly taken in Churchbay shared on Twitter.

Met Éireann has forecast that early spring sunshine will clear away mist and fog on Saturday morning and it will be another dry and pleasant day with spells of sunshine. However, it is possible that fog will linger along some coasts through the day. Highest temperatures of 13 to 17 degrees are expected in a light breeze.

On Sunday, any mist and fog will clear early in the morning as good, long, sunny spells develop across the country. It will stay mainly dry too but a little bit of cloud will bubble up in the west. Highs will reach 13 to 17 degrees with light southeasterly winds. 

In the evening the clear skies will allow some mist and fog patches to form. Overnight lows of 1 to 4 degrees with light winds are forecast. Temperatures reached highs of 18 degrees Celsius in various parts of the country on Friday with 0mm of rain reported at the time of print.

The Portuguese Man o' War jellyfish, which has reportedly been seen in some Cork beaches in recent days, can grow up to 12 inches long and five inches wide. Its tentacles can reach 165 feet. Their venom is used to paralyse and kill prey, and the sting can cause severe pain for days. Although very rare, Man o' War stings can sometimes kill humans.

Jellyfish numbers will increase in Irish waters over the next few months according to CEO of Irish Water Safety John Leech. In cooler months, jellyfish will typically live near the bottom of the seabed but as the temperatures rise, they also rise to the surface.

Mr Leech said:

Each summer, we are seeing more and more jellyfish. Global warming and overfishing are the two main reasons for this. 

"When the jellyfish are small, fish will feed on them. But if we don’t have those fish to eat those smaller jellyfish, because they have been fished, these jellyfish will continue to breed in very large numbers and that’s what we’re seeing.” 

According to Mr Leech, the number of sightings of the lion’s mane jellyfish — Ireland’s most dangerous species of jellyfish — have been prevalent in areas where they wouldn’t normally be seen.

“A lion’s mane jellyfish went up the Shannon estuary as far as Glin Pier in County Limerick — that is unheard of. Nobody has ever seen a lion’s mane in Limerick before but that gives you an idea of the large number of them," he says.